some fixes for pandocListItemContinuation

re: issue #114

Author: fmoralesc

syntax/pandoc.vim

@@ -433,7 +433,7 @@ syn match pandocListItem /^\s*(\?x\=l\=\(i\{,3}[vx]\=\)\{,3}c\{,3}[.)].*$/ nextg
 syn match pandocListItemBullet /^(\?.\{-}[.)]/ contained containedin=pandocListItem
 syn match pandocListItemBulletId /\(\d\+\|\l\|\#\|@.\{-}\|x\=l\=\(i\{,3}[vx]\=\)\{,3}c\{,3}\)/ contained containedin=pandocListItemBullet
 
-syn match pandocListItemContinuation /^\s\+\(\([-+*]\|(\?.\+[).]\)\@<![[:alpha:]ñäëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß]\)\@=.*$/ nextgroup=pandocLaTeXMathBlock,pandocLaTeXInlineMath,pandocDelimitedCodeBlock,pandocListItemContinuation,pandocListItem contains=@Spell,pandocEmphasis,pandocStrong,pandocNoFormatted,pandocStrikeout,pandocSubscript,pandocSuperscript,pandocStrongEmphasis,pandocStrongEmphasis,pandocPCite,pandocICite,pandocCiteKey,pandocReferenceLabel,pandocLaTeXMathBlock,pandocLaTeXInlineMath contained skipempty display 
+syn match pandocListItemContinuation /^\s\+\(\([-+*]\|(\?.\+[).]\)\@<![[:alpha:]ñäëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_"]\)\@=.*$/ nextgroup=pandocLaTeXMathBlock,pandocLaTeXInlineMath,pandocDelimitedCodeBlock,pandocListItemContinuation,pandocListItem contains=@Spell,pandocEmphasis,pandocStrong,pandocNoFormatted,pandocStrikeout,pandocSubscript,pandocSuperscript,pandocStrongEmphasis,pandocStrongEmphasis,pandocPCite,pandocICite,pandocCiteKey,pandocReferenceLabel,pandocLaTeXMathBlock,pandocLaTeXInlineMath contained skipempty display 
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